In recent years, demand for a display unit having low power consumption and high image quality has been increased as various electronic apparatuses such as a mobile phone or a mobile information terminal device (PDA) have become widespread. In particular, in accordance with the birth of electronic-book delivery business, attention has been recently paid to an electronic book terminal for reading application that is used for a purpose of reading literal information for a long time. A display unit having a display quality suitable for that application has been therefore desired.
For the reading application, there has been proposed a display unit of a cholesteric liquid crystal type, an electrophoretic type, an electric redox type, a twist-ball type, etc. In particular, a display unit classified into that of a reflective type may be preferable. This is because the reflective display unit utilizes reflection (scattering) of outside light to perform bright display as with paper, and therefore achieves display quality close to that of the paper. It is also because consumed power is suppressed as a result of unnecessity of a backlight.
A leading candidate of the reflective display unit is an electrophoretic display unit that utilizes electrophoresis phenomenon to generate brightness and darkness (contrast). This is because the electrophoretic display unit is low in power consumption and superior in high-speed responsiveness. Accordingly, various considerations have been made on a display method of the electrophoretic display unit.
Specifically, there is proposed a method in which two kinds of charged particles that have different optical reflection characteristics and different polarities are dispersed in insulating liquid, and the difference in polarity is utilized to move the respective charged particles (for example, see Patent Literatures 1 and 2). In this method, distribution of the two kinds of charged particles varies depending on an electric field, and contrast is generated thereby utilizing the difference in optical reflection characteristics.